It takes some time when sound reaches our ear from its source. The distance travelled by sound in one second is called velocity of sound. The velocity of sound depends on some factors.
Nature of medium: Velocity of sound in different media is different. For example velocity of sound in air, water and iron is different. At 20°C the velocity of sound in air is 344 ms-1, in water it is 1450 ms-1 and in iron it is 5130 ms-1. Generally we can see the velocity of sound in air is less, in liquid it is higher and highest in solid.
Temperature: The more the temperature increases, the more the velocity of sound in the air increases. For this reason, the velocity of sound is more in summer than that of in winter.
(Calculate: The velocity of sound is 344 ms-1 at 20°C temperature and 332 ms-1 at 0°. How much does the velocity of sound increases for the increase of temperature by 1°C?)
Humidity of air: The velocity of sound increases with the increase of humidity. For this reason, the velocity of sound is more in the humid air than that of in thy air.